System, circuit and method for tuning a resonant circuit

Abstract

A circuit may be tuned to resonate at a driving frequency. The circuit includes a source that provides an output at a drive frequency and a resonant circuit having an input coupled to the source, an output, and first and second selectable resonant frequencies. The first resonant frequency is below the drive frequency and the second resonant frequency is above the drive frequency. A control coupled to the resonant circuit output selects the first and second resonant frequencies to cause the resonant circuit to provide an output at an apparent resonant frequency equal to the drive frequency.

Description

CLAIM OF PRIORITY[0001]This application claims priority to U.S. Provisional Application Ser. No. 60 / 632,721, filed on Dec. 1, 2004, which is incorporated by reference.BACKGROUND OF THE INVENTION[0002]Implantable medical devices for remedial treatment of and compensation for cardiac, neural and muscular disorders are known in the art. These devices range from cardiac pacemakers as described in U.S. Pat. No. 4,712,555 to Thornander et al., to microstimulators as described in U.S. Pat. No. 6,208,894 to Schulman et al. The quest for minimization of such devices, especially in the area of microdevices such as microstimulators and microsensors continues. Paramount in this quest has been the challenge of efficiently providing a reliable and stable power source to power the device or charge its internal battery. The quest has further addressed the communication medium to facilitate information, data and command signal transfer and exchange between the microdevice and a corresponding microde...

AI Technical Summary

Benefits of technology

The invention provides a circuit and method for controlling the resonant frequency of a resonant circuit. This is achieved by using a control circuit that selects the first and second resonant frequencies, which can be either a series or parallel tuned resonant circuit. The control circuit can be responsive to various characteristics of the resonant circuit, such as current output or phase-shift, and can selectively vary the resonant frequency to achieve apparent resonance at the drive frequency. The technical effect of this invention is to provide a more efficient and effective means for controlling the resonant frequency of a resonant circuit, which can be useful in various applications such as communication devices or sensors.

Problems solved by technology

Paramount in this quest has been the challenge of efficiently providing a reliable and stable power source to power the device or charge its internal battery.

Unfortunately, such ideal circumstances are generally not possible and the effective inductance value of the inductor often is caused to change.

Changes in inductance value of the inductor may have a severe impact on the resonant frequency of the tuned circuit.

This results in a correspondingly negative effect on the magnetic field generated by the inductor.

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